A typical such ventral plate is formed with a plurality of holes for receiving bone screws that pass through the holes and that are to be screwed into the vertebral bodies of adjacent vertebras.
Bone plates for osteosynthesis have been known for a long time and are employed in particular in order to cover sites of fractures. Moreover, they are also employed in surgery on the spinal column for stiffening adjacent vertebral bodies. However, it is disadvantageous that with the known bone plates the surgeon cannot see the areas covered by the plate, which is particularly disadvantageous in spinal column surgery when, after the plate has been placed, the surgery must be continued for adding bone, bone cement, or another substitute element for the spinal column.
It has been suggested in U.S. Pat. No. 6,585,738 of Mangione and EP 1,121,903 of Calisse to use an L-shaped or U-shaped bone plate, but such a structure is often insufficiently strong. The bone plate, which is secured at each end by two screws, is subjected to considerable stress and failure could result in a serious spinal injury.